Experimental Study of Temperature-Dependence Laws of Absorption Line Shape Parameters based on an Analysis of CO2 v3 Transmittance Spectra

Abstract

To improve the understanding of temperature-dependence laws of spectral line shape parameters, spectra of the v3 rovibrational band of CO2 perturbed by 10, 30, 100, 300 and 1000 mbar of N2 were recorded at nine temperatures between 190 K and 330 K using a 22 cm long single-pass absorption cell in a Bruker IFS 125HR Fourier Transform spectrometer. The spectra were fitted employing a quadratic speed-dependent hard collision model in the Hartmann-Tran implementation (Ngo et al., 2013, 2014; Tran et al., 2013, 2014) extended to account for line mixing in the Rosenkranz approximation by means of a multispectrum fitting approach developed at DLR (Loos et al., 2014). This enabled high accuracy parameter retrievals to reproduce the spectra down to noise level and the variation of line widths, shifts, speed-dependence-, collisional narrowing- and line mixing-parameters over this 140 K temperature range is presented.